Pentreath is a surname. Notable people with the surname include:
Ben Pentreath, English architectural and interior designer David Pentreath (1933–2019), Royal Navy officer and pilot Dolly Pentreath (1692–1777), Cornish fishwife Guy Pentreath (1902–1985), headmaster of many Anglican schools Jonathan Pentreath (born 1966), Royal Navy senior officer Richard John Pentreath, British marine scientist Timothy Pentreath McClement (born 1951), Royal Navy officer